Hello GRW (No first name? No presentation as it is customary here?)

The 37777 is a Schienenzepplin reeleased in 2010
Here is the user's manual in case you don't have it
https://static.maerklin....2f3cfa795d1434542357.pdf
Address in MM2 = 60 (if not changed by the previous user).
MM2 is the only protocol available on your 6021

One possibility is that your 6021 is not set foir MM2
Here is the 6021 manual in case you don't have it
https://static.maerklin....1189fe42a71434542461.pdf
Normally, all 4 rear switches should be OFF except switch 2 that must be ON (both Motorola and MM2 protocols are activated)
All rear switches OFF on the 6021 are only for Motoroila (NOT MM2)

If you have a white Märklin transformer, you may check if the direction change works DON'T DO IT with a blue transformer.
If it works, chances are your decoder is OK and could need a RESET

If you could have access to an MFX station (MS2 or CS3) it would be much easier to analyse and reset

NOTE: to program CVs with a 6021, I suggest you read this thread and especially post #2
https://www.marklin-users.net/fo...-Programming-with-M-6021

RESET is made by writing CV8 = 8

Cheers
Jean

Edited by user 22 December 2024 14:38:19(UTC)  | Reason: Not specified